Imaging, data acquisition, data transmission, and data distribution methods and systems for high data rate tomographic X-ray scanners

ABSTRACT

The present invention is an X-ray system having a source-detector module, which includes X-ray sources and detectors, for scanning an object being inspected, a scan engine coupled to the source-detector module for collecting scan data from the source detector module, an image reconstruction engine coupled to the scan engine for converting the collected scan data into one or more X-ray images, and a scan controller coupled with at least one of the source detector module, the scan engine, and the image reconstruction engine optimize operations of the X-ray system.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application relies on U.S. Patent Provisional ApplicationNo. 61/181,077 filed on May 26, 2009, for priority.

The present application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/485,897, filed on Jun. 16, 2009, which is acontinuation of U.S. patent application Ser. No. 10/554,656, filed onOct. 25, 2005, and now issued U.S. Pat. No. 7,564,939, which is a 371national stage application of PCT/GB04/01729, filed on Apr. 23, 2004 andwhich, in turn, relies on Great Britain Application No. 0309387.9, filedon Apr. 25, 2003, for priority.

The present application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/371,853, filed on Feb. 16, 2009, which is acontinuation of U.S. patent application Ser. No. 10/554,975, filed onOct. 25, 2005, and now issued U.S. Pat. No. 7,512,215, which is a 371national stage application of PCT/GB2004/01741, filed on Apr. 23, 2004and which, in turn, relies on Great Britain Application Number0309383.8, filed on Apr. 25, 2003, for priority.

The present application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/651,479, filed on Jan. 3, 2010, which is acontinuation of U.S. patent application Ser. No. 10/554,654, filed onOct. 25, 2005, and now issued U.S. Pat. No. 7,664,230, which is a 371national stage application of PCT/GB2004/001731, filed on Apr. 23, 2004and which, in turn, relies on Great Britain Patent Application Number0309371.3, filed on Apr. 25, 2003, for priority.

The present application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/364,067, filed on Feb. 2, 2009, which is acontinuation of U.S. patent application Ser. No. 12/033,035, filed onFeb. 19, 2008, and now issued U.S. Pat. No. 7,505,563, which is acontinuation of U.S. patent application Ser. No. 10/554,569, filed onOct. 25, 2005, and now issued U.S. Pat. No. 7,349,525, which is a 371national stage filing of PCT/GB04/001732, filed on Apr. 23, 2004 andwhich, in turn, relies on Great Britain Patent Application Number0309374.7, filed on Apr. 25, 2003, for priority.

The present invention is also a continuation-in-part of U.S. patentapplication Ser. No. 12/758,764, filed on Apr. 12, 2010, which is acontinuation of U.S. patent application Ser. No. 12/211,219, filed onSep. 16, 2008, and now issued U.S. Pat. No. 7,724,868, which is acontinuation of U.S. Pat. No. 10/554,655, filed on Oct. 25, 2005, andnow issued U.S. Pat. No. 7,440,543, which is a 371 national stageapplication of PCT/GB2004/001751, filed on Apr. 23, 2004, and which, inturn, relies on Great Britain Patent Application Number 0309385.3, filedon Apr. 25, 2003, for priority.

The present application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/697,073, filed on Jan. 29, 2010, which is acontinuation of U.S. patent application Ser. No. 10/554,570, filed onOct. 25, 2005, and now issued U.S. Pat. No. 7,684,538, which is a 371national stage application of PCT/GB2004/001747, filed on Apr. 23, 2004,and which, in turn, relies on Great Britain Patent Application Number0309379.6, filed on Apr. 25, 2003, for priority.

The present application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/097,422, filed on Jun. 13, 2008, and U.S. patentapplication Ser. No. 12/142,005, filed on Jun. 19, 2008, both of whichare 371 national stage applications of PCT/GB2006/004684, filed on Dec.15, 2006, which, in turn, relies on Great Britain Patent ApplicationNumber 0525593.0, filed on Dec. 16, 2005, for priority.

The present application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/478,757, filed on Jun. 4, 2009, which is acontinuation of U.S. patent application Ser. No. 12/364,067, filed onFeb. 2, 2009, which is a continuation of U.S. patent application Ser.No. 12/033,035, filed on Feb. 19, 2008, and now issued U.S. Pat. No.7,505,563, which is a continuation of U.S. patent application Ser. No.10/554,569, filed on Oct. 25, 2005, and now issued U.S. Pat. No.7,349,525, which is a 371 national stage filing of PCT/GB04/001732,filed on Apr. 23, 2004 and which, in turn, relies on Great BritainPatent Application Number 0309374.7, filed on Apr. 25, 2003, forpriority. In addition, U.S. Patent Application number relies on GreatBritain Patent Application Number 0812864.7, filed on Jul. 15, 2008, forpriority.

The present application is also a continuation-in part of U.S. patentapplication Ser. No. 12/712,476, filed on Feb. 25, 2010, which relies onU.S. Provisional Patent Application No. 61/155,572 filed on Feb. 26,2009 and Great Britain Patent Application No. 0903198.0 filed on Feb.25, 2009, for priority.

Each of the aforementioned PCT, foreign, and U.S. applications, and anyapplications related thereto, is herein incorporated by reference intheir entirety.

BACKGROUND OF THE INVENTION

Applicant has developed a new generation of X-ray systems that implementX-ray sources with more than one electron gun and one or more highvoltage anodes within a single vacuum envelope.

The rapid switching of electron guns under electrostatic control enablesthe fast movement of the effective focal spot of the X-ray tube and therapid generation of sets of tomographic X-ray scan data without the useof moving parts. By configuring the firing sequence of the electron gunsappropriately, an optimal set of X-ray projection data can be collectedat rates far higher than in conventional systems.

Accordingly, because Applicant's latest generation X-ray tomographysystems are capable of generating very high resolution tomography X-raydata at high speeds, a number of new data acquisition and datatransmission and distribution systems are enabled, and/or required, totake full advantage of, and/or optimally manage, these high data ratesystems. For example, current storage systems and data transmissionnetworks are unable to effectively transfer high volumes of image datato network of operator workstations without undue delay. Moreover, suchdelay increases as the number of image generating systems on a networkincreases and as the number of operators required to analyze images alsoincreases.

Therefore, improved data acquisition, transmission and distributionsystems arc needed to take full advantage of, and/or optimally manage,high resolution X-ray data generated at high speeds, such as data ratesgreater than 1 Gbit/second.

SUMMARY OF THE INVENTION

In an embodiment, the present invention provides an X-ray systemcomprising: a source-detector module comprising a plurality of X-raysources and detectors for scanning an object being inspected; a scanengine coupled to the source-detector module for collecting scan datafrom the source detector module; an image reconstruction engine coupledto the scan engine for converting the collected scan data into one ormore X-ray images; and a scan controller coupled with at least one ofthe source detector module, the scan engine, and the imagereconstruction engine, and a user input module for providing controlinformation based on at least one of: user constraints obtained via theuser input module, the scan data and the X-ray image data, the controlinformation optimizing operations of the X-ray system dynamically. TheX-ray system further comprises a data visualisation engine coupled tothe image reconstruction engine for rendering the image data to a humanreadable screen and one or more storage devices coupled to one or moreof the source detector module, the scan engine, and the imagereconstruction engine for storing data obtained therefrom.

In an embodiment, the scan engine co-ordinates the source-detectormodule, and is programmable on a scan-by-scan basis and within a scan,thereby allowing for rapid re-optimization of the source-detectormodule. The scan controller optimizes the scan engine by analyzing thescan data for identifying one or more regions comprising requiredinformation, and controlling the scan engine to collect scan data onlyfrom the X-ray sources and detectors corresponding to the one or moreidentified regions. In an embodiment, the scan data is analyzed by usinga sinogram chart to obtain a region of interest, the sinogram chartcomprising data from each detector arranged in a horizontal row and datafrom each X-ray source rotation angle arranged in consecutive rows toform a two dimensional data set, and the region of interest is obtainedby obtaining a trajectory thorough the sinogram data set correspondingto at least two required points in the object being inspected.

In an embodiment, the scan controller optimizes the image reconstructionengine by providing control information directing the imagereconstruction engine to convert only a predefined portion of scan datainto an X-ray image. Further, the scan controller controls the scanengine to generate a first spatial resolution in a scan direction and asecond spatial resolution in a scan plane, the first spatial resolutionbeing lower than the second spatial resolution. Also, the scancontroller controls the spatial resolution of the scan data collected bythe scan engine dynamically, the controlled data being passed to theimage reconstruction engine for generating variable resolution imagedata.

In another embodiment, the present invention provides an imagetransmission system comprising: a plurality of X-ray systems forinspecting one or more object by using X-rays and producing at least onethree-dimensional (3D) image of each object; a plurality of 3D engines,each 3D engine being coupled with at least one X-ray system forobtaining one or more two dimensional (2D) images by processing each 3Dimage produced by the X-ray system, the 2D images being projections ofthe 3D image; at least one network scheduler coupled to each 3D enginevia a dedicated network link for rendering the one or more 2D images toone or more operators for manual inspection, each operator inspecting a2D image for obtaining one or more predefined features, the networkscheduler rendering a corresponding 3D image to an operator forinspection upon receiving a request for the same; and at least onestorage array coupled with each of the X-ray systems via a high speeddedicated network link for storing one or more of the 3D images and the2D images.

In another embodiment, the present invention is directed toward an imagetransmission system comprising a plurality of X-ray systems forinspecting one or more object by using X-rays and producing at least onethree-dimensional image of each object; a plurality of engines, eachengine being coupled with at least one X-ray system for obtaining one ormore two dimensional images by processing each image produced by theX-ray system, the two dimensional images being projections of the threedimensional image; at least one network scheduler coupled to each threedimensional engine via a network link for rendering the one or more twodimensional images to one or more operators for manual inspection,wherein the network scheduler renders a corresponding three dimensionalimage to an operator for inspection upon receiving a request for suchthree dimensional image; and at least one storage array coupled witheach of the X-ray systems via a high speed dedicated network link forstoring one or more of the three dimensional images and the twodimensional images.

In another embodiment, the present invention is directed toward an X-raysystem comprising a plurality of detectors for generating raw X-raydata; a scan engine coupled to the plurality of detectors for receivingthe raw X-ray data and generating calibrated X-ray data; an imagereconstruction engine coupled to the scan engine for converting thecalibrated X-ray data into one or more processed X-ray images; and ascan controller coupled with said plurality of detectors and at leastone of said scan engine or image reconstruction engine, wherein saidscan controller receives said raw X-ray data and dynamically modulatesprocessing of at least one of said raw X-ray data by said scan engine orsaid calibrated X-ray data by said image reconstruction engine.

The X-ray system further comprises a user input wherein said user inputreceives control information from a user and wherein said scancontroller uses said control information to dynamically modulateprocessing of at least one of said raw X-ray data by said scan engine orprocessing of said calibrated X-ray data by said image reconstructionengine. The raw X-ray data is transmission data. The raw X-ray data isbackscatter data. The X-ray system further comprises a datavisualization engine coupled to the image reconstruction engine forrendering the processed X-ray images to a human readable screen. TheX-ray system further comprises one or more storage devices coupled toone or more of the plurality of detectors, the scan engine, and theimage reconstruction engine for storing data obtained from the pluralityof detectors, the scan engine, and the image reconstruction engine.

The scan controller dynamically modulates the processing of said rawX-ray data by said scan engine by analyzing the raw X-ray data andidentifying one or more regions comprising required information. The oneor more regions comprising required information is a subset of allregions detected by said plurality of detectors, e.g. not all regionscontain required information and only those regions that do aresubjected to calibration or image processing.

The scan controller issues instructions to the scan engine to processraw X-ray data only from detectors corresponding to the one or moreregions comprising required information. The scan controller issuesinstructions to the image reconstruction engine to process calibratedX-ray data only from detectors corresponding to the one or more regionscomprising required information. The X-ray system further comprises adata visualization engine wherein said data visualization enginereceives from said image reconstruction engine a plurality ofcoordinates corresponding to the one or more regions comprising requiredinformation.

In another embodiment, the X-ray system comprises a source of radiationhaving a scan rotation; a plurality of detectors for generating rawX-ray data; a scan engine coupled to the plurality of detectors forreceiving the raw X-ray data and generating calibrated X-ray data; animage reconstruction engine coupled to the scan engine for convertingthe calibrated X-ray data into one or more processed X-ray images; and ascan controller coupled with said plurality of detectors and at leastone of said scan engine or image reconstruction engine, wherein saidscan controller receives said raw X-ray data and dynamically modulatesat least one of said source of radiation or scan engine based on saidraw X-ray data. The scan controller issues instructions to said scanengine to modify a spatial resolution of a scan based upon said rawX-ray data. The spatial resolution is modified by generating a firstspatial resolution in a scan direction and a second spatial resolutionin a scan plane, the first spatial resolution being different than thesecond spatial resolution.

The scan controller issues instructions to said scan engine to generatea first resolution in a scan and a second resolution in the scan whereinsaid first resolution and said second resolution are different. The scanengine transmits said scan having the first resolution and the secondresolution to the image reconstruction engine. The image reconstructionengine generates image data having variable resolution based on saidscan having the first resolution and the second resolution. The imagereconstruction engine generates image data having at least one area ofcoarse pixelation, medium granularity pixelation, or high granularitypixelation. The scan controller issues instructions to at least one ofsaid scan engine or source of radiation to control a rotation rate ofsaid source of radiation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one embodiment of the X-ray system of thepresent invention;

FIG. 2 depicts an imaging area relative to the object being inspected;

FIG. 3 depicts an exemplary sinogram generated by the present invention;

FIG. 4 depicts a variable scan, based on the object being scanned;

FIG. 5 is an exemplary diagram of variable pixelation levels of anobject being scanned;

FIG. 6 is a diagram of a collection of X-ray systems with improved datatransmission; and

FIG. 7 depicts exemplary two-dimensional images derived from a fullthree-dimensional data set.

DETAILED DESCRIPTION OF THE INVENTION

The X-ray systems disclosed in the above-mentioned applications, whichare herein incorporated by reference, enable the rapid and real-timecontrol of X-ray source trajectories. The present invention takesadvantage of this capability by dynamically controlling X-ray sourcetrajectories and dynamically altering the image reconstruction methodsbased on both the properties of the object under investigation and thequality of the inspection decision that is required. This dynamic systemoptimization can have several benefits, including reduction of scandose, reduction of computation complexity and reduction of databandwidth. Other objectives can be addressed using the same and relatedoptimization methods.

The following disclosure is provided in order to enable a person havingordinary skill in the art to practice the invention. Exemplaryembodiments are provided only for illustrative purposes and variousmodifications will be readily apparent to persons skilled in the art.The general principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the invention. Also, the terminology and phraseology used is for thepurpose of describing exemplary embodiments and should not be consideredlimiting. Thus, the present invention is to be accorded the widest scopeencompassing numerous alternatives, modifications and equivalentsconsistent with the principles and features disclosed. For purpose ofclarity, details relating to technical material that is known in thetechnical fields related to the invention have not been described indetail so as not to unnecessarily obscure the present invention.

The present invention will now be discussed in context of embodiments asillustrated in the accompanying drawings. Referring to FIG. 1, oneembodiment of an X-ray system configuration is shown. The X-ray system100 comprises a set of X-ray sources and X-ray detectors 105 which arecapable of collecting information about the object under inspection. Theset of sources and detectors (sensors) 105, are, in one embodimentconfigured to generate transmitted X-ray data set suitable fortomographic image reconstruction. Alternatively, in another embodiment,the set of sources and sensors 105 are configured to generate a set ofdiffraction X-ray data or a set of backscattered X-ray data.Alternatively, in yet another embodiment, sources and sensors 105 areconfigured to generate a set of stereoscopic transmission X-ray data.One of ordinary skill in the art would appreciate that the presentinvention can be applied to other source and sensor geometries.

As shown in FIG. 1, a scan engine 110 coordinates scanning of the objectunder inspection and data collection from the X-ray sources anddetectors 105. The scan engine 110 is programmable on a scan-by-scanbasis and also within a scan to allow rapid re-optimization of the X-raysystem 100.

As shown in FIG. 1, an image reconstruction engine 115 takes the rawdata and/or calibrated data which is output from the scan engine 110 andconverts this data into a recognizable set of image data or processeddata. It should be appreciated that calibrated data can be generatedfrom a pre-processor which is part of the scan engine 110 and which canalso be considered the first stage of the image reconstruction engine115.

For example, suppose that the scan engine 110 normally provides a set ofcalibrated transmission X-ray projection data. The image reconstructionengine 115 takes this projection data and converts this data into anX-ray image using a plurality of processing techniques such as filteredback projection to convert the projection data back into a 2- or3-dimensional tomographic X-ray image. As used herein, raw data refersto data directly transferred from one or more detectors or detector datathat has not yet been subject to calibration or normalization. Raw datawhich has been subject to calibration or normalization is referred to ascalibrated data. Processed data or image data is calibrated data thathas been passed through one or more filters.

Processed data from the image reconstruction engine 115 is optionallypassed to an optional data visualization engine 120. The datavisualisation engine 120 takes the reconstructed image data and rendersit to a human readable screen. This data visualization engine 120, inone embodiment, is capable of performing functions such asinterpolation, three-dimensional projection into a two-dimensionalimage, and image coloring based on reconstructed image density,materials type or other parameters as required.

In one embodiment, a storage device 125, such as a RAID array, set ofhard disks, or other memory systems, is provided for archiving X-rayimage data. It will be understood by an expert that the storage device125 shall be capable of storing data from any point in the signal chain,and not just at the output of the data visualisation engine.

The scan controller 130 is capable of interpreting X-ray image data atthe output from all components in the imaging chain. The scan controller130 is also capable of outputting control information to all componentsin the imaging chain. In this way, the scan controller 130 has theability to optimize the entire system operation.

The scan controller 130 also receives input data from a user inputstation 135, in which users can input their constraints on the imageoptimization process via, for example, a touch screen, mouse, orkeyboard in communication with a computing device. For example, in asecurity screening system the user may select a current threat level(e.g. High, Medium or Low). In a medical system, the user may select adose or spatial resolution constraint (e.g. High Diagnostic Quality, LowDose).

The scan controller 130 thus takes input from two different sources,namely user constraints and X-ray image data, and implements a methodwhich processes the X-ray image data according to the user constraintsin order to continually and dynamically re-optimize the operation of theX-ray sources and detectors 105, the scan engine 110, the imagereconstruction engine 115, and/or the data visualisation engine 120.

It should be appreciated that the functions and features of the X-raysources and detectors 105, scan engine 110, image reconstruction engine115, and/or data visualization engine 120, as described herein, areenabled by hardware, such as servers comprising at least one processor,executing a plurality of programmatic instructions which are stored in amemory, such as RAM, ROM, hard disk, or other memory structures. Thevarious engines may be integrated into one or more servers which areremote or local to one another. The components of the X-ray system 100may therefore be local or remote from each other, may be integrated intoa single server or distributed among a plurality of servers across anetwork, and/or may communicate with each other through any wired orwireless form of transmission and reception. It should further beappreciated that each engine comprises at least one data receiver, datatransmitter, and data processor capable of executing a plurality ofprogrammatic instructions, stored in memory, to perform the functionsand features of the engines, as described herein.

Referring to FIG. 2, in one embodiment, the tomographic X-ray imagingsystem of the present invention images an object 210 which partiallyfills the imaging area 205. Conventionally, a rotating gantry X-raysource is used and projection data is accumulated for all projectionangles and from all detector elements. It is computationally expensiveto collect and process all of this data when only a fraction of theX-ray inspection area is actually filled with a relevant object. Thefraction of the X-ray inspection area which is filled with air 225 orthe object support 220 is generally of little interest to the user.

In one embodiment, this scanning scenario can be improved in thefollowing manner. Rather than scan and process the entire imaging area205, raw scan data generated by the X-ray system is first analyzed bythe scan controller 130. Regions of the image data that contain relevantinformation are differentiated from those areas which contain norelevant data. As shown in FIG. 3, a sinogram chart 300 can be used toreview the data. The chart 300 arranges data from each detector in ahorizontal row (from −d/2 through 0 to +d/2 where d=total number ofdetectors in a projection) and data from each source rotation angle(from Phi_1 to Phi₁₃ n where n=number of projection angles) inconsecutive rows to form a two dimensional data set. The trajectorythorough the sinogram data set for two points in the object, labelled A305 and B 315, is also shown in the diagram.

In the present invention, once the first line of the sinogram (Phi_1)has been collected, it is known, a priori, what part of the sinogramwill need to be collected at all other projections angles. The scancontroller can therefore optimize the scan engine to only collect andprocess data from those detector elements which are actually needed,e.g. would actually generate relevant data, thereby saving on front enddata bandwidth and computer power.

Mathematically, the sinogram data is linked forward to the backprojectedimage by the Radon Transform. Under this transform, each point in thesinogram represents one backprojected line through the reconstructedimage. Since it is known which parts of the sinogram contain usefuldata, and hence were collected by the scan engine, the imagereconstruction engine is therefore constrained to only filter andbackproject the valuable parts of the sinogram data. This can yieldmajor savings in computational cost in the image reconstruction engine.

The image reconstruction engine is typically designed to permit fullimage reconstruction of the whole image reconstruction circle at fullreconstructed image slice rate. Very often, only a fraction of the imagereconstruction circle has an object therein, and systems designed withthe use of the scan controller can be provided with a much lower costimage reconstruction engine that is optimized to dynamically reconstructonly the relevant part of the object. Preferably, the scan engine andimage reconstruction engine shall comprise, or have access to, a buffermemory to allow sequences of images where the object is larger than thedesigned image reconstruction circle fill capacity to be storedtemporarily until the image reconstruction engine has caught up with thecurrent data flow.

The data visualisation engine is provided with the coordinates (such asslice number and position within the slice) of the sub-image which isprovided by the image reconstruction engine and it uses thesecoordinates (slice number and position within the slice) to referencethe reconstructed image data to the appropriate part of thethree-dimensional reconstructed image volume prior to datavisualization. The net effect is a substantial reduction in databandwidth to the storage system. This simplifies design of networkattached storage and reduces the cost of storage solutions sinceunwanted background data is not stored.

In a further example of the use of this invention, it may be the casethat the object to be inspected has variable inspection significancealong its length. For example, some parts of the human body are quitesymmetric in the scan direction (the legs) and here it may beadvantageous to design a tomographic image system which generates alower spatial resolution in the scan direction (along the legs) comparedto that in the scan plane.

To do this, the user may request the scan controller to use a low dosescanning method, which could be achieved by dynamically controlling thescan rotation rate to allow a degree of scan-direction partial volumeartifact when imaging the long bones of the leg in order to reduce dose.Referring to FIG. 4, when arriving at the knees 402 which aresubstantially variable in the scan direction, the scan controller canautomatically direct the scan engine to increase scan rate (and hencealso X-ray dose) in order to create a high-resolution image of the knees402 prior to returning to a lower dose rate once back to the long bones404 past the knee.

Mathematically, the scan controller can determine the rate of change ofinformation in the scan direction by subtracting each new sinogram fromthe previous sinogram and the difference is an indication of the rate ofchange of information in the scan direction.

In a further embodiment of this invention, it is possible to use thescan controller to adjust, on a dynamic basis, the spatial resolution inthe data collected by the scan engine. This data is then passed throughto the image reconstruction engine which in turn provides a variableresolution image. The reconstructed image is encoded for display by thedata visualization engine so that the image is represented correctly inboth the spatial and time domains.

As an example, in a security inspection application providingthree-dimensional tomographic image reconstruction, one can reconstructlow density regions, such as clothes, with coarse pixelation 515 (suchas greater than ten times the smallest pixel size), reserving mediumgranularity pixelation 525 (such as 2-10 times the smallest pixel size)and high granularity pixelation 530 (such as the smallest pixel size,i.e. 1 mm×1 mm) for complex objects, such as a lap-top computer, whichresembles a higher-threat object, as shown in FIG. 5. By relaxing theresolution requirements in some areas, and thus requiring lesscomputation, the spare computation capacity can be allocated to provideenhanced resolution in complex areas of the image. The net effect is areduction in data bandwidth, a reduction in computational cost and areduction in storage requirements with little detriment to diagnosticquality.

In one embodiment, the sinogram data directs the scan controllerregarding what computational power should be allocated in order to formthe reconstructed image. Sinogram regions that exhibit a high degree ofvariation, such as those regions with a smaller signal to noise ratio(i.e. a ratio of less than 20, preferably less than 10), are linkeddirectly to those areas of the reconstructed image where a high imageresolution should be achieved. A high image resolution is typically lessthan 2 mm×2 mm×2 mm in terms of pixel size, while a low image resolutionis typically greater than 5 mm×5 mm×5 mm in terms of pixel size. Regionsof the sinogram that exhibit a low degree of variation, such as thoseregions with a higher signal to noise ration (i.e. a ratio of greaterthan 40, preferably greater than 50), are linked to those areas of thereconstructed image where a low image resolution can be tolerated.

One of ordinary skill in the art would appreciate that the variableresolution reconstructed image should be encoded such that the datavisualization engine can reference the variable resolution reconstructedimage data into the appropriate locations in the three-dimensional dataset for human display purposes. It is further understood that suitableimage processing methods, such as three-dimensional image interpolation,can be used to render an image with uniformly high spatial resolution tothe screen even though the underlying data may have been reconstructedat variable resolution.

In a further embodiment of this invention, it is recognized that thenature of the image reconstruction process itself can be affected by theinformation that is being processed by the scan engine. By way ofexample, consider an imaging system which is typically looking for lowatomic number, low contrast objects in a uniform matrix. Such an imageis suited to a filtered backprojection tomographic image reconstructionapproach. Suppose that there is, from time to time, a contaminant thatis of high atomic number which enters the imaging volume. In this case,the high atomic number material is likely to result in unwanted beamhardening artifact which can distort the analysis of the low atomicnumber materials. There are known iterative processes which are betterat minimizing the effect of beam hardening than typical filteredbackprojection algorithms. In this case, the scan controller can inspectthe sinogram for particularly highly attenuating objects and cansubstitute iterative algorithms for those regions where the highlyattenuating objects are located, and can apply the less computationallydemanding filtered backprojection algorithm to all other areas of theimage. The result is a minimization in beam hardening artifact and animprovement in ultimate image analysis.

It shall be evident to one skilled in the art that it is possible toapply the methods described here simultaneously and individuallydepending on the optimization requirements that have been set by theuser, on the cost constraints that were evaluated at the time of systemmanufacture, and on the availability and performance of storage systems.

As discussed above, the high data rate, high throughput system requiresan improved image transmission system to provide a responsive, scalableand cost effective transmission method. Referring to FIG. 6, acollection of X-ray systems 605, each capable of generating high volumesof data where each data set comprises a three-dimensional image of anobject, is shown. Each X-ray system 605 is provided with a high speeddedicated network link which can take this three-dimensional data setdirectly to a high capacity storage array 645 at full bandwidth withlittle latency.

The database on the storage array 645 is managed by a system server 655which is connected to the X-ray systems 605 and to the disk controller665 via a network. A series of operators view three-dimensional imagedata at a series of networked workstations 635.

A job dispatcher application executes on the system server 655 andrecognizes when new three-dimensional data is available. The jobdispatcher application allocates a particular operator to review the newthree-dimensional data set and the operator reports his or her findingsback to the system server 655 via the network. At this point, thethree-dimensional data set may be discarded, or it may be archived formedium term or long term storage.

Such a system can be very slow and use very large amounts of networkbandwidth due to the size of the three-dimensional data sets. In thepresent invention, a 3D engine component 615 is coupled to the system,one 3D engine 615 per X-ray system 605. The 3D engine 615 processes thefull three-dimensional data set that is generated by the X-ray system605 in real time since it is directly connected to the X-Ray system 605rather than being constrained by the bandwidth and latency of anintermediate network.

The 3D engine 615 processes the X-ray system 605 data into one or moretwo-dimensional images which represent projections through thethree-dimensional data. Example two-dimensional images 700 that arederived from a full three-dimensional data set are provided in FIG. 7.The images 700 depict a three-dimensional triangular object and a cubelike object in various orientations. It shall be evident to one skilledin the art that the size of the two-dimensional image is small comparedto that of the full three-dimensional data set. Therefore, the networktransmission time for the 2D image is short compared to that for thefull 3D data set.

In the present invention, the 3D engine 615 output connects directly tothe network such that the job dispatcher application running on thesystem server 655 can first dispatch a set of compact 2D images to anoperator workstation 635 for immediate review. As a minimum, one 2Dimage will be rapidly generated and dispatched to the operator. Moretypically, 5 to 8 2D images will be pre-rendered and dispatched to anoperator workstation 635. Very frequently, the operator can inspect theobject with sufficient integrity that they do not need access to thefull three-dimensional data set, thereby permitting the operatorworkstation 635 to be of a relatively low specification and reducing itscost compared to a full 3D workstation. The network can be almost anycommercially available network of moderate bandwidth, such as a gigabitethernet network.

In the event that the inspector can not inspect the object using 2Dimages only, the operator can signal to the job dispatcher thatinspection is incomplete and that the image data should be transferredto a fully 3D operator workstation with a suitably trained operator forfurther review.

In this case, the job dispatcher will locate a suitably qualified 3Doperator and will first send the set of 2D images to the operator forreview. At this point, the operator will start to analyze the image datafrom 2D images only. In the background, the job dispatcher will start totransfer the full 3D data set to the 3D operator. Once the 3D data sethas arrived at the operator workstation, the 3D engine inside theoperator workstation will prepare the data set for 3D review by theoperator. When the 3D data set is ready for viewing, the imageworkstation enables a set of three-dimensional image analysis tools andthe operator can start to make use of these in an interactive fashion.The operator thus transfers from a 2D inspection mode to a 3D inspectionmode as the necessary data becomes available.

Such a two-stage image transmission approach minimizes the time takenfor the operator to start work but still provides all the data forreview when needed. This is achieved using networks of modest bandwidthand latency with a consequently low cost.

In another embodiment, a network of operators, all of whom are qualifiedto inspect 3D data and all of whom have access to a 3D operatorworkstation, is provided. In this case, the operator will receive 2Ddata immediately, and can request full 3D image data when he or she isunable to complete his or her inspection using 2D pre-rendered imagesonly. Again this allows a high reliability low cost network to beutilized while maintaining high inspection throughput.

While the exemplary embodiments of the present invention are describedand illustrated herein, it will be appreciated that they are merelyillustrative. It will be understood by those skilled in the art thatvarious changes in form and detail may be made therein without departingfrom or offending the spirit and scope of the appended claims.

I claim:
 1. An X-ray system comprising: a plurality of detectors forgenerating raw X-ray data; a scan engine coupled to the plurality ofdetectors for receiving the raw X-ray data and generating calibratedX-ray data; an image reconstruction engine coupled to the scan enginefor converting the calibrated X-ray data into one or more processedX-ray images; and a scan controller coupled with said plurality ofdetectors and at least one of said scan engine or image reconstructionengine, wherein said scan controller receives said raw X-ray data anddynamically modulates processing of at least one of said raw X-ray databy said scan engine or said calibrated X-ray data by said imagereconstruction engine, wherein the scan controller dynamically modulatesthe processing of said raw X-ray data or calibrated X-ray data byanalyzing the raw X-ray data or calibrated X-ray data and identifyingone or more regions comprising required information.
 2. The X-ray systemof claim 1 further comprising a user input wherein said user inputreceives control information from a user and wherein said scancontroller uses said control information to dynamically modulateprocessing of at least one of said raw X-ray data by said scan engine orprocessing of said calibrated X-ray data by said image reconstructionengine.
 3. The X-ray system of claim 1 wherein said raw X-ray data is atleast one of transmission data and backscatter data.
 4. The X-ray systemof claim 1 wherein said scan controller is configured to direct the scanengine to increase a scan rate for a first region and decrease a scanrate for a second region, wherein the first region has a higher rate ofchange of information than the second region.
 5. The X-ray system ofclaim 1 further comprising a data visualization engine coupled to theimage reconstruction engine for rendering the processed X-ray images toa human readable screen.
 6. The X-ray system of claim 1 furthercomprising one or more storage devices coupled to one or more of theplurality of detectors, the scan engine, and the image reconstructionengine for storing data obtained from the plurality of detectors, thescan engine, and the image reconstruction engine.
 7. The X-ray system ofclaim 1 wherein said scan controller determines a rate of change ofinformation in a scan direction by subtracting each newly generatedsinogram from a previously generated sinogram and wherein said scancontroller, based upon said rate of change of information, directs thescan engine to change a scan rate for a region containing saidinformation.
 8. The X-ray system of claim 1 wherein the one or moreregions comprising required information is a subset of all regionsdetected by said plurality of detectors.
 9. The X-ray system of claim 1wherein the scan controller issues instructions to the scan engine toprocess raw X-ray data only from detectors corresponding to the one ormore regions comprising required information.
 10. The X-ray system ofclaim 1 wherein the scan controller issues instructions to the imagereconstruction engine to process calibrated X-ray data only fromdetectors corresponding to the one or more regions comprising requiredinformation.
 11. The X-ray system of claim 1 wherein the imagereconstruction engine is configured to generate a variable resolutionimage, wherein a part of the variable resolution image with lowercomplexity has a lower resolution and a part of the variable resolutionimage with higher complexity has a higher resolution.
 12. An X-raysystem comprising: a source of radiation having a scan rotation; aplurality of detectors for generating raw X-ray data; a scan enginecoupled to the plurality of detectors for receiving the raw X-ray dataand generating calibrated X-ray data; an image reconstruction enginecoupled to the scan engine for converting the calibrated X-ray data intoone or more processed X-ray images; and a scan controller coupled withsaid plurality of detectors and at least one of said scan engine orimage reconstruction engine, wherein said scan controller receives saidraw X-ray data and dynamically modulates at least one of said source ofradiation or scan engine based on said raw X-ray data wherein the scancontroller is configured to direct the scan engine to increase a scanrate for a first region and decrease a scan rate for a second region,wherein the first region has a higher rate of change of information thanthe second region.
 13. The X-ray system of claim 12 wherein the scancontroller issues instructions to said scan engine to modify a spatialresolution of a scan based upon said raw X-ray data.
 14. The X-raysystem of claim 13 wherein said spatial resolution is modified bygenerating a first spatial resolution in a scan direction and a secondspatial resolution in a scan plane, the first spatial resolution beingdifferent than the second spatial resolution.
 15. The X-ray system ofclaim 12 wherein the scan controller issues instructions to said scanengine to generate a first resolution in a scan and a second resolutionin the scan wherein said first resolution and said second resolution aredifferent.
 16. The X-ray system of claim 15 wherein said scan enginetransmits said scan having the first resolution and the secondresolution to the image reconstruction engine.
 17. The X-ray system ofclaim 16 wherein said image reconstruction engine generates image datahaving variable resolution based on said scan having the firstresolution and the second resolution.
 18. The X-ray system of claim 16wherein said image reconstruction engine generates image data having atleast one area of coarse pixilation and at least one area of highgranularity pixelation.
 19. The X-ray system of claim 12 wherein thescan controller issues instructions to at least one of said scan engineor source of radiation to control a rotation rate of said source ofradiation.
 20. The X-ray system of claim 12 wherein said scan controllerdetermines a rate of change of information in a scan direction bysubtracting each newly generated sinogram from a previously generatedsinogram and wherein, based upon said rate of change of information,said scan controller directs the scan engine to change a scan rate for aregion containing said information.